RT-20 · Equipment

Medical Gas Supply & Cylinder Systems

Cylinder duration math, safety index systems, regulators, and bulk supply — the calculation questions you can guarantee will appear.

~16 min read3 concept sections·2 questions with rationale

What you'll be able to do

  • Calculate remaining cylinder duration for oxygen and heliox
  • Identify safety indexing systems and cylinder color codes
  • Distinguish regulators, reducing valves, and flowmeters
  • Recognize bulk supply and zone valve emergencies
Concept breakdown
01

Cylinder duration is a guaranteed calculation

Duration in minutes equals gauge pressure times the cylinder factor, divided by flow in L/min.

  • Cylinder factors: E = 0.28, H/K = 3.14, D = 0.16, G = 2.41.
  • A full E cylinder holds about 660 L at 2200 psi; a full H cylinder about 6900 L.
  • Example: an E cylinder at 1500 psi running 4 L/min lasts (1500 × 0.28) / 4 = 105 minutes.
  • Change the cylinder at roughly 500 psi — that is the safe residual, not empty.
  • Heliox flow through an oxygen flowmeter must be corrected: 80/20 heliox multiply the reading by 1.8; 70/30 by 1.6.
At the bedside

Before transport, run the math out loud and add a margin. A cylinder that lasts exactly as long as the trip is a cylinder that runs out.

Practice quiz

Check yourself before you read the rationale.

Question 1 of 1

An E cylinder gauge reads 1200 psi and the patient is on 6 L/min. Approximately how long will the cylinder last?

Practice questions

Answer first, then read why the distractors fail.

Question 1

An E cylinder gauge reads 1200 psi and the patient is on 6 L/min. Approximately how long will the cylinder last?

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2 more concept sections, 1 more question, and the exam-day playbook for this module.

The free preview above gives you the opening concept, sample quiz, and practice questions. Unlock the full module for every breakdown, bedside note, rationale-driven question, and the test-day playbook.

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